The present disclosure relates to processes useful in providing catalysts having a high surface area.
Active catalysts may be used in many applications, for example, air filtration, effluent pollution control, hydrocarbon cracking, and solid oxide fuel cells. For some applications, it may be desirable to control the surface area of the catalyst material, in order to control the catalysis rate. Thus, a very high surface area may be desirable to provide very fast reactions. For example, many materials exist that are useful as anodes and cathodes in solid oxide fuel cells (SOFC). Such materials include nickel oxide, various compounds of La, Sr, Mn, O, Ni, Co, Zr, Y, and the like, as well as combinations thereof including such as La0.75Sr0.25Cr0.5Mn0.5O3. These materials may be deposited onto ceramic backbone particles, such as yttrium stabilized zirconia (YSZ), of controlled size, shape and porosity to generate large surface area materials coated by a thin layer of electrode material in a so-called “supported electrode” construction of SOFC.
Processes to coat ceramic backbone materials in supported electrode SOFC, including physical or chemical vapor deposition techniques, are expensive.
Emulsion aggregation is a process that may be used, in some instances, to produce toners for electrostatographic apparatuses. For example, U.S. Pat. No. 5,853,943, the disclosure of which is hereby incorporated by reference in its entirety, is directed to a semi-continuous emulsion polymerization process for preparing a latex by first forming a seed polymer. Other examples of emulsion/aggregation/coalescing processes for the preparation of toners are illustrated in U.S. Pat. Nos. 5,403,693, 5,418,108, 5,364,729, and 5,346,797, the disclosures of each of which are hereby incorporated by reference in their entirety. Other processes are disclosed in U.S. Pat. Nos. 5,527,658, 5,585,215, 5,650,255, 5,650,256 and 5,501,935, the disclosures of each of which are hereby incorporated by reference in their entirety.
Improved methods for producing catalysts, which reduce environmental concerns and increase the effectiveness of the catalyst by providing catalysts with a high surface area, as well ability to tailor the catalyst structure, remain desirable.